Microstructure evolution and mechanical properties of the Sip/Zn-Al composite joints by ultrasonic-assisted soldering in air

Hypereutectic Al-27Si alloys were joined without flux by ultrasonic-assisted soldering at 420 ℃ in air using Zn-5A1 the filler alloys,and Si particulate-reinforced Zn-Al based composites filler joints were obtained.The ultrasonic vibration introduced into soldering could influence the migration of Si particles and the microstructure of solidified Zn-Al based alloys.Both the distribution of Si particles and microstructure of the solidified Zn-Al based alloys affected the shear strength of joints.The shear strength increased with the ultrasonic vibration time.The highest average shear strength of joints reached to ～ 68.5 MPa.Transcrystalline rupture mode was observed on the fracture surface.